Datasheet

Table Of Contents
Section 22 Power-Down Modes
REJ09B0140-0900 Rev. 9.00 Page 695 of 846
Sep 16, 2010
H8S/2215 Group
22.5.4 Hardware Standby Mode Timings
Timing of Transition to Hardware Standby Mode
1. To retain RAM contents with the RAME bit set to 1 in SYSCR
Drive the RES signal low at least 10 states before the STBY signal goes low, as shown in
figure 22.5. After STBY has gone low, RES has to wait for at least 0 ns before becoming high.
t
2
0 ns
t
1
10 t
cyc
STBY
RES
Figure 22.5 Timing of Transition to Hardware Standby Mode
2. To retain RAM contents with the RAME bit cleared to 0 in SYSCR, or when RAM contents do
not need to be retained
RES does not have to be driven low as in the above case.
Timing of Recovery from Hardware Standby Mode
Drive the RES signal low and NMI signal high approximately 100 ns or more before STBY goes
high to execute a power-on reset.
t
OSC
t
NMIRH
t 100 ns
STBY
RES
NMI
Figure 22.6 Timing of Recovery from Hardware Standby Mode